The measurement of any displacements between two substantially coaxial parts mounted on one another can have a number of purposes. One of them consists, for example, in preventing a potential defect in the link between the two parts, as a function of the measured displacements, such as angular displacements and/or linear displacements. The tracking of these measurements can also make it possible to check that the measured displacements conform to those determined by computation in the design phase.
Whatever the application envisaged, there is a need to provide a measurement device that is simple, reliable and of little bulk, specifically designed to measure displacement between two substantially coaxial parts mounted on one another, preferably by a link of annular linear type.